Few question that there was a major chemical attack in Syria last week , and the United States has made clear that it blames the government of President Bashar al-Assad .

Now , the question is how President Barack Obama will respond .

For almost two years , Obama has avoided direct military involvement in Syria 's civil war , only escalating aid to rebel fighters in June after suspected smaller-scale chemical weapons attacks by Syrian government forces .

However , last week 's attack on a Damascus suburb that reportedly killed and wounded more than 3,000 people obliterated the `` red line '' Obama set just over a year ago against the use of Syria 's chemical weapons stocks .

At the White House , spokesman Jay Carney told reporters Monday that Obama was evaluating `` a response to the clear use on a mass scale with repugnant results of chemical weapons , '' adding that `` there is very little doubt that the Syrian regime ... used those weapons . ''

Meanwhile , U.S. Secretary of State John Kerry called the attack `` inexcusable '' and `` undeniable , '' and said there was `` a clear reason that the world has banned entirely chemical weapons . ''

He said that evidence `` strongly indicates '' chemical weapons were used in Syria and that `` we know the Syrian regime maintains custody '' of such weapons and has the rockets to use them .

Read Kerry 's remarks

Obama `` will be making an informed decision about how to respond to this indiscriminate use '' of chemical weapons , Kerry added , saying the president `` believes there must be accountability '' for those who use them .

Options available to Obama range from ordering limited missile strikes to continued diplomatic efforts labeled by critics as a `` do-nothing '' approach .

Obama will be presented with final options regarding actions against Syria in the next few days , a senior administration official said Monday . Assuming the president decides to go ahead with a military response , any action could come as early as mid-week , though it could be later , the official cautioned .

Factors weighing into the timing of any action include a desire to get it done before the president leaves for Russia next week and before the administration has to make a decision on whether to suspend aid to Egypt because of the ongoing political turmoil there , the official explained . The administration also wants it to be a quick response to the use of chemical weapons , the senior administration official said .

American officials are consulting with allies to ensure they are supportive of any U.S. action , which the senior administration official said would be very limited in scope and a direct reaction to the use of chemical weapons . And three representatives of allied governments involved in those top-level consultations said the goal is to reach a consensus as soon as possible .

`` No one is talking about a long process , '' one European diplomat told CNN .

Marie Harf , a State Department spokeswoman , said any U.S. response would be `` a determination on how to respond to a blatant use of chemical weapons , and it 's not necessarily to change the entire situation on the ground in Syria . ''

That might be a mistake , said Michael Doran , an analyst at the Brookings Institution 's Saban Center for Middle East Policy . A U.S. strike `` ca n't just be one and done , '' but should be part of a plan to remove al-Assad , he told CNN 's `` Anderson Cooper 360 . ''

`` The president has been very reulctant to get involved . Public opinion has been against it . There 's not a lot of support on the Hill , '' Doran said . `` And yet , here we are again . Time and time again , we get dragged further and further in . '' The result could be `` a Vietnam-type problem , where we kind of back our way into this , if we do n't come up with a plan about how to win . ''

Kerry spoke with his British , Jordanian , Qatari and Saudi counterparts Monday and with the secretary-general of the Arab League , Harf said .

`` Obviously , the intelligence assessment is ongoing , '' she said . `` But he reiterated that the president is studying the facts and will be making an informed decision about how to respond going forward . ''

The Obama administration is expected to declassify the intelligence assessment backing up its assertion that the Syrian regime was responsible for last week 's chemical weapons attack , another senior administration official said . The declassification would happen before any U.S. military action would take place .

A senior administration official familiar with the intelligence told CNN that the evidence `` includes but is not limited to '' satellite images of activity at Syrian military installations identified as including chemical weapons depots .

Earlier Monday , a White House official ruled out sending ground troops to Syria or implementing a no-fly zone to blunt al-Assad 's aerial superiority over rebels fighting to oust his regime . The official insisted that all other options were under consideration by Obama but put no time frame on a decision .

Meanwhile , a senior Defense Department official told CNN 's Chris Lawrence Monday that four U.S. Navy destroyers `` maintain readiness and , if required , could execute a mission within hours '' of being ordered to do so .

But the official added that the U.S. military remained `` in a holding pattern '' as Obama considers both military and nonmilitary options .

Opinion : How Al-Assad used chemical weapons to poison debate on Syria

Also , Defense Secretary Chuck Hagel said while visiting Indonesia that any U.S. action `` will be in concert with the international community and within the framework of legal justification . ''

While U.N. Secretary-General Ban Ki-moon said Monday that the use of chemical weapons was a crime against humanity and must be punished , certain opposition by Syrian ally Russia and possibly China undermined the possibility that the Security Council would support a military mission .

Instead , a limited coalition of NATO partners such as Germany , France and Britain -- all of which have called for action against Syria -- and some Arab League members appeared more likely to provide the political backing needed by Obama to order U.S. missile strikes .

A senior administration official told CNN on Monday that the goals of any coalition military action would be to punish al-Assad and show him that there was a cost for using chemical weapons while preventing him from doing so again .

In addition , a military strike would seek to degrade the Syrian regime 's capabilities enough to weaken it without causing it to fall to an opposition considered unprepared to assume power , the official said .

Possible coalition partners include NATO allies Britain , France , Germany and Canada , as well as regional powers Qatar , Turkey , Saudi Arabia and the United Arab Emirates .

Last month , Joint Chiefs Chairman Gen. Martin Dempsey provided Congress with a list of declassified U.S. military options for Syria that emphasized the high costs and risks of what he said would amount to `` an act of war '' at a time of deep budget cuts .

U.S. official : Almost no doubt al-Assad regime used chemical weapons

Dempsey 's letter , dated July 19 , listed U.S. assets in the region including Patriot missile defense batteries in Turkey and Jordan , as well as F-16 jet fighters positioned to defend Jordan from possible cross-border trouble . In addition , the Pentagon has sent four warships armed with cruise missiles to the region .

According to U.S. officials , updated options offered the president in recent days included :

â $ cents Cruise missiles fired from one of four Navy destroyers deployed in the Mediterranean Sea . The missiles would be used to strike `` command and control '' facilities such as command bunkers , or the Syrian regime 's means of delivering chemical weapons : artillery batteries and launchers . There is no indication that the missiles would strike at actual chemical weapons stockpiles .

â $ cents Military jets firings weapons from outside Syrian airspace . This option carries additional risks and is considered less likely .

`` They have to be careful to do this in concert with our allies , '' Democratic Rep. Adam Schiff of California , a member of the House Intelligence Committee , told CNN on Sunday , adding that `` I do n't think the White House is going to want to risk American lives by sending pilots over Syria , so that really limits our options to cruise strikes and think that 's probably where the White House is going to go . ''

U.N. chemical weapons inspectors reach alleged attack site

Cruise missile strikes could be `` very punishing '' on al-Assad 's missile supplies and aircraft without going after the chemical weapons stockpiles to risk dispersing them , Schiff said .

To Aaron David Miller , a vice president at the Woodrow Wilson International Center , the situation is forcing Obama to shift from being an `` avoider-in-chief '' regarding military involvement in Syria .

`` It 's almost inevitable that the president will authorize some form of military action , '' Miller told National Public Radio in an interview broadcast Monday .

He said he expected a significant response that amounts to `` a warning that lays down this time a red line that the president intends to enforce , not one that turns pink . ''

`` It can not simply be a couple of cruise missiles into a storage shed somewhere , '' Miller said , adding that the goal was to deter al-Assad rather than topple him or radically shift the balance in Syria at this time . `` The president 's not on the verge of becoming the cavalry to rescue the country . ''

Schiff agreed that Obama has little choice but to respond strongly .

`` In terms of the credibility of the White House , '' he said , `` the cost of not acting now , I think , exceeds the cost of acting . ''

@highlight

U.S. evidence includes satellite imagery , official says

@highlight

Obama is considering how to respond to Syrian chemical attack

@highlight

Official : Obama could be presented with options within days

@highlight

A U.S. strike `` ca n't just be one and done , '' a Middle East analyst says